The node selection setting allows you to specify a groovy script to run. It accepts the "node" variable, and if the script returns true for the node, the node is considered to be one of the candidates. You may call method node.hasResource("resource name") in script to determine if a node has specified resource.

Hi Robin,

From my understanding, in my case, the groovy script needs to communicate with a database and get status of each agent. So I need to create a resource in "Grid", and in that resource I need to write the script to get the agent status, and if the status is available then return True, then set "on node with specific resource" in the Node selection and select my resource. am I right?

You mentioned that you want to run job on free agent not being booked by others. Can you please let me know how you consider a build agent is free? Does it mean that there is no other builds running on this agent? Also how you are booking a build agent and where is the book info stored? With these info, I might be able to propose a more appropriate solution.

Hi Robin,

So all information will store in our database including two tables like this. First, we will analyze the top table, first the remote session should be None which means no body is using this agent right now. And then we check the JHI status, if the status is Idle, then it is available. Final thing is to check the below table to see whether other person booked this agent, if it is booked today, then it couldn't be the candidates. So in one word, to determine whether a agent is free we need to check three things:1. remote by others? 2. Use or idle? 3. booked by others today? Only the agent which meet the remote session is none, idle status and no body book today can be seen as the candidates which means in this case only the agent 4 is free.

So it is totally not relevant to QB resource. You may edit node selection setting of the QB step and tell it to run a groovy script, and in your groovy script, connect to database and check if a given node is available, a psuedo script:

groovy:
def agentRecord = queryAgentRecord(node.hostName);
if (agentRecord != null && agentRecord.remoteSession == null && agentRecord.jhiStatus == idle) {
def bookRecord = queryBookRecord(node.hostName);
return bookRecord != null;
} else {
return false;
}

Hi Robin,

I have developed the groovy script on my own computer and it runs well. But in quick build UI, I select the node selection as "on node with specific script evaluating to true", after I copy the script to quick build and run, it shows the error. Do you know the reason why the error occurs? BTW, why the println statement in my script info didn't show in the quick build web log, because in my local computer it can show.

Hi Robin,

I have fixed that error, it's the problem of my script. Now I have face one problem which is when there is no available agent to run the build, the build will fail with the error "cannot find ant node matching specified criteria". So in this case it will stop the build right now without run. I wonder is there any setting can repeat that build in a certain periodical time if my groovy script doesn't find the free agent rather than stop it immediately. So once we have the available agent we can still build that task. Thanks!

Thanks Robin, it works.